The purpose of the filter is to remove foreign
material from the water. These materials consist mainly of airborne
dirt and leaves, organic matter introduced by bathers, and organisms
such as bacteria and algae. Swimming pool filtration is a mechanical
straining or entrapping process. A well-designed and properly
operated filter will remove virtually all of the insoluble suspended
matter in the water producing a sparkling clean condition. It must
be recognized that a filter does not destroy living organisms such
as algae and bacteria. This is accomplished by the use of
The length of time the filter must be operated to
produce the desired clarity will vary with several conditions, some of
the most significant being:
- Number of bathers
- Degree of chlorination (covered in Pool
- Proper pH control (covered in Pool Chemistry
- Exposure to airborne contamination
There are several types of filters that may be
used on swimming pools. The most satisfactory are described below:
CARTRIDGE AND ELEMENT FILTER
Cartridge filters consist of a
removable-replaceable filter element. There are two basic types of
cartridges, namely depth and surface. Dept cartridges consist of a
thick layer of fiberous materials graded and blended to provide
thousands of tiny crevices to trap dirt. Surface cartridges are made
by pleating specially compounded paper or synthetic fabric to provide
a large area of fiber surface in a relatively small volume. The fabric
is made with controlled porosity to screen out dirt and other foreign
matter as the water passes through. When the cartridge becomes clogged
with dirt, it is removed, washed, and returned to the filter.
Successive use of the cartridge leaves a residue of dirt so that after
several cleanings the cartridge is discarded and replaced with a new
one. Having a spare cartridge to alternate in use is advisable.
Sand filters are designed to operate at various
flow rates depending on their tank and internal component
configurations. With correct distribution and flow of water, the
carefully sized sand bed will trap dirt throughout its depth thus
providing a fairly large dirt retention volume. Without correct flow
distribution, dirt may be driven through the sand without performing
its intended function. Cleaning of the sand bed is done by passing
water at high velocity in reverse (up flow) through the sand. This
causes a scrubbing action of the sand freeing the dirt, which is
carried to waste.
DIATOMACEOUS EARTH FILTER
Due to the fineness of the diatomaceous earth
particles, a high degree of filtration efficiency may be obtained with
this type of filter. A precoat layer of diatomaceous earth (filter
aid) is applied hydraulically upon the surfaces of the filter elements
or other filtration surfaces. Due to the minute pores created by this
precoat layer, very small particles are screened out as the water
passes through the filter, thus producing a highly polished sparkling
condition in the water. After the filter has removed its capacity of
dirt from the water and the flow has reduced appreciably, the clogged
filter aid is removed by one of several means and discarded to waste.
BOTTOM AND SURFACE CLEANING
Surface cleaning is accomplished by automatic
surface skimming and manual hand skimming.
FUNCTION OF SURFACE SKIMMER
The automatic surface skimmer is a device which
is attached to the pump intake line and which rests on the pool
surface. The continual flow of water from the surface of the pool
through the skimmer removes floating debris such as oils, leaves, and
other airborne materials before they settle to the bottom of the pool.
A floating weir in the skimmer automatically adjusts for variations in
the pool water level. The surface skimmer also serves as a convenient
means of introducing filter aid for precoating a diatomaceous earth
filter. NEVER ADD CHEMICALS THROUGH SKIMMER.
TYPES OF SURFACE SKIMMERS
AUTOMATIC CIRCULAR TYPE SKIMMER – This design, attached
to the suction line contains a floating weir that permits introduction
of water from all directions, thus increasing the skimmer
effectiveness. A self-contained strainer traps large particles such as
leaves and twigs to prevent their entry into the pump.
THRU-THE-WALL SKIMMER – Attached to the outer side of
the pool wall, this permanently installed skimmer collects surface
water without having any projections within the pool that might
interfere with bathers. It provides a more positive control of
skimming being rigidly mounted. A built-in strainer basket to collect
leaves and other debris is easily removed for cleaning.
HAND SKIMMER – The pool surface may be skimmed by hand
with the leaf skimmer. It consists of a dished screen net supported by
a rigid ring to which a handle is attached. By attaching an extension
handle, leaves may also be removed from the bottom of the pool.
DIRECT SUCTION CLEANER – This type of cleaner is
operated from flow produced by the filter pump. A vacuum cleaner hose
is connected between the cleaner head and the pump intake line. This
method produces an efficient means of cleaning. Sediment from the
bottom of the pool is drawn through the cleaner head to the filter
where the dirt is removed and the clear water is returned to the pool
without waste. The cleaner head is moved systematically over the floor
surface to remove all sediment. For most efficient operation, the
filter and pump strainer should be clean before operating the vacuum
leaner. Care should be used when operating vacuum cleaner in cove
area. Some vacuum heads can puncture the liner in this area.
JET VACUUM CLEANER – The operation of a jet-type cleaner
requires the use of city water pressure which is conducted to the
cleaner head through a garden hose. By means of an ejector jet built
into the cleaner, a vacuum is created which picks up sediment from the
pool floor and deposits it in a porous bag attached to the cleaner.
The suction from a pool drain can be so
powerful that it can hold an adult under water, but most incidents
involve children. The body can become sealed against the drain or hair
can be pulled in and tangled. Missing or broken drain covers are a
major reason many entrapment incidents occur. Pool and spa owners can
consider installing a Safety Vacuum Release System (SVRS), which
detects when a drain is blocked and automatically shuts off the pool
pump or interrupts the water circulation to prevent an entrapment.
time you use a pool or spa, inspect it for entrapment hazards. Check
to make sure appropriate drain covers are in place and undamaged.
Keeping your pool water in balance is a key step in
quality pool care. When your
pool water is balanced then pool care is easy. but when it becomes
unbalanced, problems can and will arise. Pool Water Balance takes
into account pH, Calcium and TA or Total Alkalinity
The table below applies to all pools.
||Frequency of Test
||Best results Range
||twice a week
Correct Levels Ensure:
Bacteria fighting power of chemicals will be at
You will not see a corrosive build up on pools or
Minimal Pool and Eye Irritations
To keep your pool balanced, test it and then add
what is necessary.
If pH is low add a pH Plus Product
Like Pool Life Plus
If pH is High add a pH Minus Product
Like Pool Life Minus
For Calcium Hardness
If Calcium is low add a water
if Calcium is High add a sequestering
For Total Alkalinity
If Alkalinity is Too high, add an
Alkalinity is Too low, add an Alkalinity
CPSC's Safety Tips For Preventing Electrocutions In
and Around the Pool
- Know where all the electrical switches and circuit breakers for
pool equipment and lights are located and how to turn them off in an
- Refrain from swimming before, during, or after thunderstorms.
- Have an electrician who is qualified in pool and spa repairs
inspect and upgrade your pool, spa or hot tub in accordance with
applicable local codes and the National Electrical Code (NEC).
- Ensure that all electrical wires and junction boxes are at least
five feet away from water, as required by the NEC.
- Protect swimmers from injury by following the NEC requirements
for installing GFCIs:
- on underwater lighting circuits operating at 120-volts (CPSC
recommends GFCIs for circuits that are 15 volts or greater);
- on pumps and electrical equipment used with pools, spas and
hot tubs, including heaters close to the pool and operated on 240
- on electrical circuits around pools, spas, and hot tubs;
- on all outdoor receptacles and receptacles within 20 feet of
the water's edge to protect people from injury.
- Test GFCIs monthly to assure continued protection. Infrequently
used and portable or cord-connected GFCIs should be tested before
each day's use. To test a GFCI:
- Plug a nightlight into the outlet and turn the nightlight on.
- Press the "TEST" button. Did the light go out? If not, replace
the GFCI or have it inspected by an electrician.
- Press the "RESET" button. Did the light come back on? If not,
replace the GFCI.
- Wear shoes while conducting the test, especially if outdoors
or standing on wet ground.
- Use battery-operated appliances instead of cord-connected
appliances in and around a pool, spa, or hot tub.
- Post an emergency plan within clear view of those using the
- Ensure that overhead power lines and junction boxes are safely
positioned when installing a new pool, hot tub or spa.
Consumer Product Safety Commission
"Spas, Hot Tubs, and Whirlpools"
The U.S. Consumer Product Safety Commission (CPSC) helped develop
standards to prevent hair entanglement and body part entrapment in
spas, hot tubs, and whirlpools. These standards should help
prevent deaths and injuries. Consumers should fix their old spas,
hot tubs, and whirlpools with new, safer drain covers. CPSC warns
about these hazards:
-- The main hazard from hot tubs and spas is the same as that
from pools - drowning. Since 1990, CPSC has reports of more than
800 deaths in spas and hot tubs. About one-fifth of those were
drownings to children under age five. Consumers should keep a
locked safety cover on the spa whenever it is not in use and
keep children away unless there is constant adult supervision.
Entanglement -- Since 1990, CPSC has reports of 43 incidents
(including 12 deaths) in which people's hair was sucked into the
suction fitting of a spa, hot tub, or whirlpool, causing the
victim's head to be held under water. Hair entanglement occurs
when a bather's hair becomes entangled in a drain cover as the
water and hair are drawn through the drain. In some incidents,
children were playing a "hold your breath the longest" game.
Permitting their long hair to be sucked into the drain. CPSC
helped develop a voluntary standard for drain covers that helps
reduce the risk of hair entrapment. Consumers should be sure
they have new drain covers that meet this standard. If you are
not sure, call a pool or spa professional to check the spa.
Never allow a child to play in a way that could permit the
child's hair to come near the drain cover. If a drain cover is
missing or broken, shut down the spa until the cover is
- Body part Entrapment -- CPSC knows
of 74 incidents since 1990 in which parts of the body have been
entrapped by the strong suction of the drain of pools, wad-ing
pools, spas, and hot tubs. Of these, two resulted in
disembowelment and 13 other people died. CPSC helped develop a
standard requiring dome-shaped drain outlets and two outlets for
each pump. This reduces the powerful suction if one drain is
blocked. Consumers with older spas should have new drain covers
installed and may want to consider getting a spa with two
- Hot Tub
Temperatures -- CPSC knows of several deaths from extremely
hot water (approximately 110 degrees Fahrenheit) in a spa. High
temperatures can cause drowsiness which may lead to
unconsciousness, resulting in drowning. In addition, raised body
temperature can lead to heat stroke and death. In 1987, CPSC
helped develop requirements for temperature controls to make
sure that spa water temperatures never exceed 104 degrees
Fahrenheit. Pregnant women and young children should not use a
spa before consulting with a physician.
CPSC recommends these safety precautions when using a hot tub,
spa, or whirlpool:
1. Always use a locked safety cover when the spa is not in use and
keep young children away from spas or hot tubs unless there is
constant adult supervision.
2. Make sure the spa has the dual drains and drain covers required
by current safety standards.
3. Regularly have a professional check your spa or hot tub and
make sure it is in good, safe working condition, and that drain
covers are in place and not cracked or missing. Check the drain
covers yourself throughout the year.
4. Know where the cut-off switch for your pump is so you can turn
it off in an emergency.
5. Be aware that consuming alcohol while using a spa could lead to
6. Keep the temperature of the water in the spa at 104 degrees
Fahrenheit or below.
Send the link for this page to a friend! Consumers can obtain this
publication and additional publication information from the
Publications section of CPSC's web site or by sending your
publication request to
This document is
in the public domain. It may be reproduced without change in part or
whole by an individual or organization without permission. If it is
reproduced, however, the Commission would appreciate knowing how it is
used. Write the U.S. Consumer Product Safety Commission, Office of
Information and Public Affairs, 4330 East West Highway, Bethesda, MD
20814 or send an e-mail to
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